Neanderthal gene variant linked to greater muscle mass in modern humans

A Neanderthal version of the growth hormone receptor causes cells to grow about 40 percent more in response to growth hormone and is associated with greater muscle mass in people who carry it today, according to a study published on Wednesday in Current Biology.news.ki+1

Ancient Interbreeding, Modern Muscles

The research, led by Hugo Zeberg of the Karolinska Institutet in Sweden and Philipp Kanis of the Max Planck Institute for Evolutionary Anthropology in Germany, found that the Neanderthal receptor differs from the most common modern human version by two amino acid changes and one small deletion. When tested in laboratory-grown cells, the Neanderthal variant triggered a markedly stronger response to growth hormone, with most of the effect traced to a single one of the two changes.discovermagazine+1

Modern humans inherited the variant through interbreeding with Neanderthals roughly 47,000 years ago. It is now especially common in South and East Asian populations, where up to 24 percent of people carry it, compared with about 0.5 percent of Europeans.news-medical+1

From Lab to Population

The team cross-referenced the laboratory findings with data from more than a million people and found that adult carriers had, on average, about 270 grams more muscle mass. No differences appeared in more than 6,000 children through age 11, suggesting the variant's effects emerge around puberty when growth hormone levels rise.discovermagazine+1

"What struck me most was that two very different types of evidence told the same story," said Kanis in a press statement. "Cells grown in the laboratory responded more strongly, while data from more than a million people showed signs of the same effect in the body. It is rare to see laboratory and population evidence fit together so clearly."news-medical

Beyond Muscle

Carriers of the variant also showed subtle skeletal differences, including a slightly shorter rear section of the lower jaw and shorter tooth roots — traits characteristic of Neanderthals.discovermagazine+1

Senior author Zeberg cautioned against overinterpretation: "This is only one of many genetic influences on growth and body shape. It cannot explain the Neandertal body type on its own, and it certainly does not determine a person's overall appearance."news-medical